Current studies include a double-blind randomized placebo controlled trial of felbamate. The unique three period cross-over design allows unbiased estimates of drug effects even in the presence of a carryover effect from one period to the next. The first study has been completed, and data analysis is in progress. We have evaluated the effect of valproic acid on cerebral glucose metabolism, using positron emission tomography (PET). This drug is of particular interest due to its possible inhibition of GABA degradative enzymes. We are comparing its effect to that of phenytoin, carbamazepine, and phenobarbital. We are evaluating optimal therapy for the Lennox-Gastaut Syndrome, comparing carbamazepine plus valproic acid to valproic acid alone.